大方廣佛華嚴經隨疏演義鈔 18.85

18.85

疏「法身非坐而坐道場」者，法身既無能所，故曰非坐。非坐之坐，湛然安住，名坐道場。

Regarding the commentary’s "The dharmakāya sits in the bodhimaṇḍa by non-sitting": since the dharmakāya has neither subject nor object, it is called "non-sitting." The sitting of non-sitting, serenely abiding securely, is called "sitting in the bodhimaṇḍa."